The present invention relates to a method and/or architecture for peripheral devices generally and, more particularly, to a method and/or architecture for a dual mode USB-PS/2 device.
A peripheral device can be added to a personal computer (PC) to provide input or to enhance functionality. Peripheral devices communicate with the PC using a signaling protocol. Two signaling protocols commonly used to interface a peripheral device (i.e., a mouse) are the Universal Serial Bus (USB) protocol (e.g., the USB Specification 1.1, published September 1998 or the USB Specification 2.0, published April 2000, etc., which are hereby incorporated by reference in their entirety) and the Personal System 2(PS/2) protocol (e.g., see IBM Personal System/2 Hardware Interface Technical Referencexe2x80x94Common Interfaces, October 1990 and the IBM Personal System/2 Mouse Technical Reference, June 1989, which are hereby incorporated by reference in their entirety). In the example of a mouse, support for both the USB and the PS/2 protocols is desirable to maximize connectivity.
In order to support both protocols, conventional peripheral devices incorporate a micro-controller connected to a set of external components that support the USB protocol and a set of external components that support the PS/2 protocols. A number of I/O pins of the micro-controller must be dedicated to selecting the proper component set for supporting the active signaling protocol. Conventional peripheral devices that support both protocols can compromise performance of one or both of the signaling modes. The micro-controllers in the conventional peripheral devices require complex firmware to manage the external components and both protocols.
Conventional peripheral devices that support both USB and PS/2 protocols can have one or more of the following disadvantages: (i) requiring higher cost due to additional external components, (ii) using more circuit board space required to support the extra components, (iii) dedicating valuable I/O pins on the micro-controller, (iv) requiring additional firmware to manage the external components, (v) requiring additional firmware to manage both protocols, and (vi) compromising the performance of one or both protocols made to support the dual modes.
A single chip solution that eliminates the need for extra components and extra I/O pins to support dual mode operation would be desirable.
The present invention concerns an apparatus comprising an integrated circuit configured to operate in a plurality of signaling protocols. The integrated circuit may be configured to automatically select one of the plurality of signaling protocols in response to a signaling protocol of a connected bus.
The objects, features and advantages of the present invention may include a method and/or architecture that may provide a dual mode device (e.g., USB-PS/2) that may (i) require no external components for dual mode (e.g., USB-PS/2) operation, (ii) share integrated circuit pins for both protocols, (iii) enable simplified firmware, (iv) eliminate polling of data lines for detecting long initial both-lines-LOW state, (v) combine both protocol features into a single chip, (vi) control signal edge rate for slow-slew rate, low-emissions operation in both modes, (v) simplify peripheral design, (vi) provide an interrupt that changes behavior depending on a selected signaling mode, and/or (vii) provide a regulator pin that may be tri-stated generally simplifying switching between modes.